Fall Style Alert: "Petrol Blue" Sports Jackets

Sophisticated but not flashy, traditional enough to fit in anywhere but racy enough to get you noticed once you’re there, the “petrol blue” sport coat (“petrol” being the Brit term for gasoline) tells the crowd you’ve got just the right amount of confidence in your tank—but no need to prove it.

A petrol blue blazer is “a great way to add a shot of color that’s still easy to wear,” says Macy’s men’s fashion director Durand Guion.

Opt for a knit, cashmere, or wool-blend jacket that’s a little shorter and closer to the body, and softly constructed, he says.

“You have to go beyond the ‘blue blazer with gold buttons’ idea—that’s not what the trend is about.”

To go casual, wear it with a light sweater, chambray shirt, or the best-quality plain cotton T-shirt you can find (“It’s not an undershirt—if it comes three to a pack, it’s not the right one,” says Guion), and pair it with dark jeans, chinos, or khakis. To get more upscale, go with a solid shirt, knit tie, and flat-front pants.

And don’t skip tailoring, he says: “If the blazer needs to be nipped in at the waist, or have the sleeves adjusted, take the time to get those details right.”